This PR adds two new LB policy extension configurations, to be used in gRPC via the new load_balancing_policy field:
* round_robin: This allows configuring the built-in ROUND_ROBIN LB policy via the new extension-based API.
* wrr_locality: This is an extension config for a new policy that does ROUND_ROBIN-style locality picking and then delegates to a child LB policy extension to pick the endpoint within the locality. This will allow users to plugin their own custom endpoint-picking logic without having to reimplement the locality-picking logic.
This is a small step toward moving away from the legacy lb_policy enum. Completing that migration will require work in Envoy to create extension configs for all built-in LB policies and register those extensions.
Risk Level: Low
Testing: N/A
Docs Changes: Included in PR
Release Notes: N/A
Platform Specific Features: N/A
Signed-off-by: Mark D. Roth <roth@google.com>
Mirrored from https://github.com/envoyproxy/envoy @ 65a82d75c3ef1e15fbc4f301c9eacc269a1a6080